No problem--you got a couple hundred million spare dollars (more like a billion, minimum) laying around to also buy & blow up 33 Arch Street with it... and then figure out what to do with the smoking hulk where both 33 Arch Street and 350 Washington Street (the garage parcel) once stood?
Because,
per Wikipedia, 33 Arch Street is 100% dependent, from a load-bearing standpoint, on the garage:
"Twenty floors cantilever over adjacent retail space and a garage, which is connected to parking on the first six levels.... The building uses four levels of external bracing to transfer the enormous loads of the high building into the small base.
The bracing continues through the parking levels to the foundation; perimeter and internal moment frames act as the lateral system above the braced levels."
Think of how messy and painstakingly difficult it would be merely to eliminate the leases for the 30+ (estimating; could be many more, given that there's 603,000 sf there
per the building website) office tenants at 33 Arch Street--including the US Securities & Exchange Commission, by the way--and have to do the same thing with 350 Washington St. Where, oh by the way, HomeGoods just opened, and they're probably only a 7 or 10 year lease.
tl; dr: we'll all be dead long long before anything happens there.
Also, this topic has been discussed at some length on AB before--not that I'm criticizing you for repeating it, it's obviously a perennially intriguing speculation because, let's face it, it's a fugly-ass garage.